Refrigerating system



Aug. 1943- D. H. KILLEFFER 2,328,462

REFRIGERATING SYSTEM Filed Sept. 28, 1939 3 Sheets-Sheet 1 E NVENTOR 04 W0 H. K/ZZEFFEP ATTORNEYS D. H. KILLEFFER REFRIGERATING SYSTEM Aug; 31, 1943.

3 Sheets-Sheet 2 Filed Sept. 28, 1939 INVENTOR A MAL FFZ-P III/I III BY M L ATTO R N EYS O m M ...m n) 1 H w M 0 m Aug. 31, 1943. D. H. KILLEFFER REFRIGERATING SYSTEM Filed Sept. 28, 1939 3 Sheets-Sheet 3 INVENTOR DA'V/D H /(/Z[[FF[ e BY M ATTORNEYS Patented Aug. 31, 1943 UNITED STATES PATENT ossic REFMGEPA'KING SYSTEM David H.1(illeffer, Crestwood, N. Y. ApplicationSeptember 28, 1939, Serial No. 296,874

12 Claims.

The present invention relates to the art of refrigeration and more particularly to methods and vention is to provide an improved arrangement for increasing the effective refrigeration available from low temperature refrigerants by interposing between the refrigerated space and the low temperature refrigerant, a heat engine which absorbs heat from the refrigerated space and converts part of it into work and transmits the remainder to the low temperature refrigerant.

Another object of the invention is to provide an arrangement whereby a volatile secondary refrigerant, such as ethyl chloride, is condensed by a low temperature primary refrigerant, such as solid carbon dioxide, and evaporated the heat of a refrigerated space and the energy is used to operate a mechanical device beyond the refrigerated space or to operate a compression refrigerating system which may additionally cool the refrigerated space.

A further object of my invention is to provide a combined solid carbon dioxide and mechanical compression refrigeration system for a chamber to be refrigerated in which a high efficiency and economy of operation are maintained.

,Another object is to provide a refrigerating system having a primary low temperature refrigerant and a secondary refrigerant with an improved device operated by the secondary refrigerant for circulating said secondary refrigerant.

Another principal object of the invention is to provide animproved arrangement for transmittingheat at a controlled rate from the refrigerated chamber to the primary refrigerant and for controlling the temperature within the refrigerated chamber.

The invention also aims to provide a prime mover capable of operating at relatively low pressure or at a relatively low difference of pressure.

The invention further aims to provide an improved prime mover wherein the friction losses are reduced to a minimum.

Still another object is to provide a prime mover included in a closed system which when installed and adjusted can be hermetically sealed to prevent leakage and in which all moving parts are so enclosed within the closed system that no moving parts extend through the walls thereof or require packing which permits movement.

This application is a continuation-impart of applicants co-pending application, Serial No. 747,548, filed October 9, 1934, now Patent No. 2,175,267, granted October 10, 1939, for Method of and apparatus for refrigeration.

The use of solid carbon dioxide commonly known as dry ice and other low temperature refrigerants of this type is especially advantageous for many types of refrigeration because of the economy, ease of handling and the possibility of controlling the temperature and of obtaining very low temperatures when desired.

The present invention provides an improved method and apparatus for using to advantage a refrigerant of the solid carbon dioxide type in combination with a secondary circulating refrigerant and especially provides for converting the heat energy absorbed by the secondary refrigerant into work outside of the refrigerated chamber.

The advantages obtainable on account of the cooling or heat exchange efficiency of low temperature refrigerants are materially increased and other beneficial results are obtained in accordance with the invention at relatively low inital cost for the low temperature refrigerants by converting a part of the heat into work. Dry ice or solid carbon dioxide which has a temperature of approximately 1l0 E2, is much used in present day refrigeration and for convenience of description it will be mentioned as the refrigerant in this description, but it is to be understood that it is mentioned by way of example and that other low temperature refrigerants operate in substantially the same way. With solid carbon dioxide at ll0 F. and refrigerator tem peratures usually in the range of about 30 to 50 F.,.depending on the nature of the materials to be kept cold, the difference in temperature is considerable and the energy available is very substantial.

The nature and objects of the invention will appear from a description of a particular embodiment thereof and an explanation of its operation for the purpose of which description and explanation reference should be had to the accompanying drawings in which- Figure 1 is a schematic drawing of a refrigerated chamber and accessory refrigerating apparatus,

not be corrosive.

Fig. 3 is a detail vertical section showing the operation of the liquid level valve control of the construction of Fig. 2,

Fig. 4 is a vertical section taken on the line 4-4 of Fig. 3,

Fig. 5 is a side elevation, with parts in section,

of the secondary refrigerating control elements of Fig. 2,

Fig. 6 is a horizontal section taken substantially on the line 6-6 of Fig. 5,

Fig. 7 is a vertical section through the fluid pump taken substantially at right angles to Fig. 5 and substantially on the line l-J thereof.

For the purposes ofillustrating the principles of the invention an embodiment will be described wherein a low temperature refrigerant, such, for example, as solid carbon dioxide, commonly known as dry ice, is contained in a suitable receptacle and heat is extracted from the refrigerated chamber by means of a low boiling point refrigerant of the type of ethyl chloride, including methyl chloride, dichloro-difluoro-methane, iso butane and others having the desired properties, which is evaporated by absorption of heat from the refrigerated chamber and then in turn is recondensed by delivering heat to the low temperature refrigerant. The refrigerant selected should preferably be one which will not solidify in the condenser, will have a substantial vapor pressure at the temperature of the refrigerated chamber but will not have too high a vapor pressure at room or shipping temperatures and will A portion of the heat absorbed by the low boiling point refrigerant in the evaporator is expended in doing mechanical work and preferably this mechanical work is in turn utilized to provide additional refrigeration for the refrigerated space or for another refrigerated space, which may be maintained at a different temperature.

In the apparatus to be more particularly described a low temperature refrigerant is stored in a suitable receptacle and a low boiling point refrigerant is circulated between the low temperature refrigerant by which it is condensed and the refrigerated chamber where it is vaporized by heat absorbed therefrom. A portion of the heat absorbed by the circulating refrigerant is expended inoperating a pump or compressor to provide further refrigeration. This secondary refrigerating circuit may operate in connection with the same or a different evaporator.

Referring more particularly to the drawings, a principal outer insulating wall of a refrigerator is indicated at 10 and an inner insulating wall ii forms a receptacle l2 for alow temperature refrigerant. Access to the chamber !2 for recharging may be had through a suitable opening in the top. A refrigerated chamber I4 is cooled by an evaporator l5 in which the low boiling point refrigerant is vaporized as it absorbs heat from the refrigerated chamber.

The construction of theevaporator He may be substantially that of a radiator and if the exposed surface is suificient the temperature within the refrigerated chamber will depend upon the boiling point of the low boiling point circulating refrigerant within the evaporator and, therefore, upon the refrigerant selected and the pressure Within the evaporator. Control of the pressure, therefore, will control the temperature. The circulating refrigerant circulates between the evap orator I 5 where it is evaporated and the condenser chamber l6 of the refrigerant receptacle l2 or at least in a position of heat exchange relation wtih the low temperature refrigerant. In accordance with 2. described embodiment of the invention provision is made for controlling the maximum pressure of the vapor. as the circulating refrigerant is boiled in the evaporator, and therefore the temperature.

As shown in the drawings the flow of circulating refrigerant from the condenser it to the evaporator l5 is actuated by fluctuating pressure in the vertical tube Hi. When the pressure is reduced refrigerant is withdrawn from the condenser !6 past the check valve l8 into the tube M and when the pressure is again increased the refrigerant is forced through the check valve l9 and conduit 2c into the evaporator. Tube i1 is connected by conduit ii to the region of fluctuating pressure in chamber 26.

Preferably the tube ii? is in contact with the wall of the condenser to keep the temperature thereof as low as possible.

The path of the vapor'from the evaporator I5 to the condenser it includes a conduit 25 to pump chamber or power chamber 26, vertical conduit 2? to the chamber 28 and conduit 29 duit 38 leads from the conduit 25 to the compressor or work chamber 3i and to cooling coil 32 and a return conduit 33 leads through the reducing valve 34 back to the inlet conduit 20 of the evaporator. The reducing valve may be of any usual type or it may even consist merely of a restricted orifice or nozzle.

Mercury movable to and fro between the power chamber 26 and the work chamber 3i acts as a working liquid and provides the pistons, in effect, for the chambers. The whole arrangement constitutes a prime mover deriving power from the vapor under pressure and a compressor arranged to compress vapor and, in the particular arrangement shown, to return the compressed vapor or liquid to the evaporator.

The construction and operation of the apparatus will be understood from a consideration of Fig. 1. As the low boiling point refrigerant vaporizes in the evaporator E5, the vapor formed passes through the conduit 25 and tends to flow into the passage 35 formed in the L-shaped block 36 within the power chamber 26 and up to the valve seat 3? beneath the v'alve 39. The opening in the valve seat, however, is of small crosssectional area and the weight of the valve 39 is sumcient to hold back the vapor and prevent its passage. The valve opening should not be too small to permit the flow necessary for effective operation.

The vapor as it is formed, however, can flow from the conduit 25 through the branch conduit 30 to the compressor chamber 3! and it forces the mercury in this chamber up through the conduit 40 and into the power chamber 26. When the mercury rises in the chamber 26 sufficiently it lifts the valve 39 which will float on mercury from its seat 31 and the vapor flows into the chamber 26. The valve shown is made of iron or steel to provide the necessary weight though floating readily on mercury. Whatever the material and the construction of the valve, it should be of such weight in proportion to the size of the aperture of the valve seat that it will effectively close and remain closed against the pressure of the vapor in the conduit 25 but it should be of such weight or otherwise so constructed that it will be liftedby the mercury or other working fluid as the same rises in the chamber 26. It is among the advantages of the particular arrangement shown that all moving parts of the valve are entirely within the closed system with no stuffing boxes or the like and in fact with no frictional moving joints yet perfect automatic control of inlet and outlet ports is attained.

As the vapor flows in, building up pressure in the chamber .26, the mercury will first flow down through the tube 40 to the lower chamber 3| and compress refrigerant gas to force it under pressure into the condenser 32 but when the mercury falls below the point 4|, where the conduit 21 joints the conduit 40 further vapor flow and build up of pressure will force the short section or plug of mercury in conduit 21 up into the chamber 28. The conduit 40 may be slightly restricted just below the chamber 25 as indicated at 44 if found desirable to improve the operation by inhibiting rapid flow of the mercury and by reducing the tendency to force a large quantity of mercury up conduit 21. Check valves 42 compressor chamber 3! insure the direction of flow. When the valve 39 is lifted by the mercury it engages the seat 45 formed on the lower end of the conduit 6 leading from the power chamber 25 to chamber 28 and as long as the pressure in the chamber 26 is substantially higher than in the chamber 28, as is the case while the mercury is flowing down during its compressing action and until the slug of mercury in the conduit is forced up through the conduit 21, the valve 39 will be held against this seat to close this communication. The space between the top of the the valve 39 and the seat 45 should be small in order that the valve may be sure to seat to close the outlet 46 immediately upon rising from the seat 31. In practice the desired result is not difficult to obtain because the vapor flowing in to the mercury through the valve seat 31 tends to raise the level of the mercury and thereby to increase the lifting force acting on the valve.

When the mercury has moved sufiiciently and vapor flows through the conduit 21 the pressure in the two chambers will be equalized and the valve will drop on to its seat 31, thus opening free communication through conduit 46. The mercury which as a slug in conduit 21 has moved into the upper chamber 28 now flows down through conduit 46 and if the valve 39 has not dropped will insure such action. The conduit 21 enters the chamber 28 horizontally and substantially tangent to the cylindrical wall, a feature which decreases spattering of the mercury and tends to delay somewhat the falling of the mercury onto the valve 39. This delay tends with other elements of the operation to permit a momentary blowing through of the vapor from the evaporator. From the point of view of increasing the circulation of refrigerant in its cycle this is advantageous. As permitting vapor to pass to the condenser without doing mechanical work, it is undesirable. In practice this and other. phases of the operation must be adjusted to meet the requirements of the installation.

The length of the conduit 40 determines the weight of the column of mercury to be lifted in each movement and, therefore, the pressure that the vapor in the evaporator l and chamber 31 must attain to cause flow of the mercury. Inasmuch as the pressure and temperature are inter-dependent functions of the particular liquid used as the low boiling point circulating refrigerant, the working temperature within the re frigerated chamber may be varied by changing the length of the column of mercury. Provision and 43 at the inlet and outlet or the for such variation of the length of the column of mercury is indicated diagrammatically in the drawings, wherein telescoping joints 48 are shown as provided in the conduits to permit the chamber 3| to be moved vertically without disarranging the connections. A second possible position 53f the chamber 31 is indicated in dot and dash ines.

The length of conduit 21 determines the weight of mercury to be lifted by the Vapor pressure in the power chamber 26 during the operation which equalizes pressure in the chambers 26 and 28 to permit the valve 39 to drop. Accordingly the working temperature within the refrigerated chamber may be varied by changing the length of this column of mercury. Telescoping joints 49 and an adjustable connection 29 make possible the adjustment. In short, the working temperature of the evaporator can be adjusted by adjustment of the effective length of either column. The efiective length or the column not selected for control should be equal to or less than the length of the controlling column.

If the secondary refrigerating circuit includes its own separate evaporator either within the same refrigerated chamber or in another refrigerated chamber, the conditions and dimensions tion after adjustment can be determined in accordance with the principles above outlined and others well understood.

It will be understood that the telescoping joints are shown more as a diagrammatic illustration than as a best practical construction. Actually the joints should be hermetically sealed as by welding to prevent any possible leakage in operahas been made at installation. An equivalent adjustment can be ar-. ranged by the use of connecting pipes that can be bent to change the relative level of one chamber.

The vapor passing from the evaporator 15 to the prime mover and compressor is at a temperature below the temperature of the refrigerated chamber whereas the power unit and compressor elements are, or may be, considerably warmer. For this reason it is desirable to provide suitable heat exchange units between conduits containing vapor (or liquid if any) flowing in opposite directions. For this purpose a heat exchange unit 52 is provided between the conduit 25 carrying vapor from the evaporator 15 to the pump and conduit 29 carrying vapor from the chamber 28 to the condenser it. Another heat exchange unit diagrammatically indicated at 53 is provided between the conduit 33, also carrying vapor from the evaporator L5 to the compressor and cooling coil 32 and the return conduit 33.

Whether the vapor is sufficiently condensed and cooled by the compressor and cooling coil 32 to reduce it to liquid condition. or not, it will be returned to the system through expansion I of refrigerant so that suitable working levels of the refrigerant in either container will not be exceeded. The capacity of the chambers 25 and 3| relative to the capacity of the evaporator should be selected in view of the preferred speed of operation of the prime mover and compressor.

and the proportion of the power available in the system which may effectively and profitably be used in doing work. The relative size of the power chamber 26 and of the GVaDOI'BtOI' I5 and the details of the mechanical arrangements will afiect the quantity of vapor which blows through at the end of each operation. It would even be possible, if found desirable, to practically prevent the blow through of any substantial quantity of refrigerant vapor as, for example, by providing a. U-shaped section at the top of the vertical conduit 21, so positioned that the slug of mercury which is forced from the conduit 21 up to the chamber 28 would be projected immediately into the conduit 46, thereby immediately closing the valve 39. Obviously this would change somewhat the operation of the arrangement shown wherein the conduit 21, chamber 28, and conduit 46 with associated parts constitute an automatic means for avoiding excessive pressure in the evaporator.

It will be obvious that the diilerence in level between the valve 39 and the work chamber or compressor chamber 3! should not be more than the length of the column of mercury which is eil'ectively supported by the difference in vapor pressure between the refrigerant in the evaporator at the temperature to be maintained in the refrigerator chamber and the vapor pressure of the refrigerant in the condenser I6.

Another embodiment of the invention is illustrated in Figs. 2 to 'l. The general arrangement of this embodiment and in general the operation are the same as that of the apparatus shown in Fig. 1. The principal outer wall of a refrigerator is indicated at H and an inner wall III forms a receptacle M2 for a low temperature refrigerant. A refrigerated chamber I is cooled by an evaporator H5. The circulating refrigerant circulates between the evaporator IIS and the condenser H0 within the refrigerant receptacle II2.

The flow of circulating refrigerant from the condenser H0 is controlled by a float controlled valve In, the float N8 of which will rise in the condenser to open the valve when a suflicient quantity of liquid refrigerant is condensed within the condenser I I6. When the valve I I1 is opened the circulating refrigerant will flow through the conduit II9 to the reservoir I20 within the re- Irigerated chamber which reservoir is subject to the temperature of the refrigerated chamber. The outlet of this chamber may be controlled by a spring pressed valve I2I which will be held closed when the pressure in the conduit I2l leading to the evaporator H is suiiicient to hold back the column of liquid and will be released when the pressure is reduced during operation. An adjusting nut I22 may be provided to control the tension of the spring I23 of the check valve.

Various other arrangements may be made for feeding liquid refrigerant from-the reservoir I20 into the circuit within the refrigerated chamber.

The vapor from the evaporator I I5 flows to the ondenser H6, through a conduit I25, power chamber I 26, vertical conduit I21. the chamber I28 and conduit I29. A branch conduit I30 leads from the conduit I25 to the compressor chamber I1" and to cool ng coil I32 and a return conduit I33 leads th ough nozzle I34 back to the inlet conduit I2I' of the evaporator.

The construction and operation of the vapor driven prime mover and compressor with con-' necting apparatus are similar in principle to that of the arrangement shown in Fig. 1. As the low boiling point refrigerant vaporizes in the evapchamber I26 and up to the valve seat E31 138-- neath the valve I39. The ball valve E33 holds back the vapor and prevents its pasage.

The vapor as it is formed, however, can flow from the conduit I25 through the branch conduit I30 to the compressor chamber Bi and it forces the mercury in this chamber up' through the conduit I40 past the check valve Hi and into the chamber i26. when the mercury rises in the chamber 520 sufliciently it lifts the valve I30 from its seat l3! and the vapor flows into the chamber 528 and by its pressure forces the mercury up through the conduit i2! and into the chamber E28; When the valve 38 is lifted by the mercury, it engages the seat M5 formed on the lower end of the conduit 5 leading to chamber I28 and as long as the pressure in the chamber 526 is substantially higher than in the chamber I28, as is the case while the mercury is being forced up through the conduit 52? the valve we will be held against this seat to close this communication. The conduit t2? extends nearly to the bottom of, the power chamber I26 and at its to enters the chamber 528 tangentially so that the flow of mercury into the chamber will involve as little spattering as possible for the reason that a spattering of the mercury into the outlet conduit I20 is objectionable for obvious reasons. The diameter of the conduit i 21 is preferably relatively large so that when the mercury is discharged from the chamber I25 and the vapor follows the mercury up the conduit to the chamber I20 there will be little if any entrainment of mercury with the vapor.

When the mercury has been completely pumped and vapor flows through the conduit I2! the pressure in the two chambers will be equalized and the ball valve will drop on to its seat E31, thus opening free communication through conduit 6. The mercury which has been forced into the upper chamber 523 flows down through conduit M1 to compressor chamber I3I and compresses the vapor of the low boiling point refrigerant which has previously come from the evaporator II5 through conduits I25 and I30 and forces the compressedvapor into the cooling coil I32. Check valves I40 and I49 in the conduit I30 insure the direction of flow. A check valve I50 may also be provided in conduit I" if desired to prevent flow of mercury up the conduit as the pressure fluctuates.

The length of the conduits I21 and I40 determines the weight of be lifted in eachmovement and therefore the pressure that the vapor in the chamber I26, chamber BI and evaporator II5 must attain to cause flow of the mercury. Inasmuch as the pressure and temperature are inter-dependent functions of the particular liquid used as the low boiling point circulating refrigerant, the temperature within the refrigerated chamber may be varied by changing the lengths of the columns of mercury and of the conduits. Provision for such variation of the length of the column of mercury is indicated diagrammatically in the drawings wherein the conduits I 21, I40, I46 and MT are shown as provided with telescoping joints to permit the chambers I28 and to be moved vertically withoutdisarranging the connections. A second possible position of the chamber I28 is indicated in dot and dash lines. As in the case of the structure shown in the column of mercury to.

Fig. 1 the telescoping joints may be in fact welded when adjusted.

A heat exchange unit I52 is provided between the conduit I25 carrying vapor from the evaporator M to the power unit and conduit I29 carrying vapor from the chamber I28 to the condenser IIB. Another heat exchange unit I53 is provided between the conduit I30, also carrying vapor from the evaporator H5 to the compres- $01 and cooling coil I32 and the return conduit Whether the vapor is sufficiently condensed and cooled by the compressor I3I and cooling coil I32 to reduce it to liquid condition, or not, it will be returned to the system through expansion valve at I34.

The float controlled valve H1 is shown more in detail in Fig. 3. The arm I55 carrying the float H8 is pivoted at I56 on a fixed pivot. As the float lifts, a plunger I51 moves inwardly until it engages and lifts a ball valve I58 from the valve seat I59 against the tensionof a spring I50 A spring I6| surrounding the plunger I51 urges the ball from the seat I59 and, therefore, when the valve is once moved to open position it is held there permitting flow of the liquid refrigerant a little longer than might otherwise be the case. The tension of the springs I50 and IBI is, of course, adjusted to attain the results desired.

The foregoing particular description is illustrative merely and not intended as defining the limits of the invention. Various modifications may be made without departing from the principles of the invention.

For example, in order to provide an automatic adjustable control of the temperature in the refrigerated chamber, flow of the circulating refrigerant into the evaporator and also flow of the refrigerant from the evaporator-could be controlled by valves at the inlet and outlet of the evaporator which in turn would be under the control of thermostats in the refrigerated chamber. The valve at the inlet would restrict flow when the temperature within the chamber reaches a predetermined point. Preferably the valve at the inlet would be so constructed that it would not at any time entirely prevent flow of refrigerant into the evaporator. This provision would avoid the possibility of a stoppage in the operation of the apparatus in the event that all of the refrigerant in the evaporator should evaporate and leave the apparatus in a non-starting condition It will be understood. upon analysis, that under certain conditions of pressure in the tube I'I refrigerant liquid might not flow to the evaporator even after the valve was opened. a

The thermostatically controlled valve at the outlet could be set to the same or a slightly different temperature to provide for the closing of the valve, thereby stopping circulation of the refrigerant when the temperature in the refrigerator reaches the predetermined limit. In some cases it may be desirable to connect both valves, at the inlet and at the outlet, for simultaneous operation by one thermostat. The valve at the outlet may be so constructed that it will entirely .close the outlet conduit and yet, because of the conditions of operation of the apparatus, there is not so great a risk that the apparatus Will not again resume its normal operation.

The power unit and compressor unit have been hereinbefore described as accomplishing their particular function in the refrigerator system herein described.

In another aspect this unit is a prime mover capable of many uses not only in refrigerator systems but in other situations where gas or vapor under pressure is available. The power unit described is particularly adapted for use where the gas or vapor under pressure is corrosive or otherwise destructive to packing glands of usual types, or where the pressure available is relatively low so that it is diflicult to pack joints such as are usually required in prime movers to prevent, leakage of vapor, gas or air to or from the system and at the same time permit movement of parts without friction, but the system is in no sense limited to such uses. The principles of the invention can be applied to apparatus designed for use under varying conditions including con.- ditions of high pressure. The prime mover described comprises a working liquid which conveniently maybe mercury as shown with some advantages inherent in the use of mercury, but it may be any other suitable liquid.

In the arrangement shown the work chamber or compressor chamber of the system is far enough below the level of the. power system to take advantage of the hydrostatic head in order to meet the requirements of compressing the vapor of the low boiling refrigerant and forcing it back into the evaporator from which it comes and from which the power -for operating the prime mover is derived. With different requirements other arrangements would be made. The pressure in the work chamber will be equal to the pressure in the power chamber plus (algebraically) the difierence in hydrostatic head of the column of mercury or other working liquid in the .system and therefore may be adjusted to meet various requirements.

it is to be noted that the prime inover shown operates between the pressure in the evaporator and the pressure in the condenser as between higher and lower pressures but that although in the system described the lower pressure is a relatively high vacuum this is merely an incident to the particular system and in no sense indicates limitation as to the absolute pressures with which the power unit may be used. The requisite for power is a difference of pressures, with substantially no limitation as to what the absolute pressure may be at the inlet ort and exhaust ports of the power chamber.

I claim:

1. In heat exchange apparatus of the refrigeration type the combination with a refrigeration chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a condenser for a low boiling point refrigerant in heat exchange relation with said low temperature refrigerant receptacle. an evaporator to evaporate said low boiling point refrigerant by absorption of heat from said chamber, a circuit through which said low boiling point refrigerant can flow from the condenser to the evaporator and back to the condenser, means actuated by the expanding'low boiling point refrigerant as it absorbs heat from the refrigerating chamber to cause intermittent flow of the vapor of the low boiling point refrigerant from the-evaporator to the condenser, said means including a chamber and a Working liquid movable to and from said chamber and acting as a piston therein.

2. In heat exchange apparatus of the refrigeration type the combination with a refrigeration chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a condenser for a low boiling point refrigerant in heat exchange relation with said low temperature refrigerant receptacle, an evaporator to evaporate said low boiling point refrigerant by absorption of heatfrom said chamber, a'circuit through which said low boiling point refrigerant can flow from the condenser to the evaporator and back to the condenser, means actuated by the expanding low boiling point refrigerant as it absorbs heat from the refrigerating chamber to cause flow of condensed low boiling point refrigerant from the condenser to the evaporator, said means including a chamber and a working liquid movable to and from said' chamber and acting as a piston therein.

3. In heat exchange apparatus of the refrigeration type the combination with a refrigeration chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a low boiling point refrigerant in heat exchange relation with said low temperature refrigerant receptacle, an evaporator to evaporate said low boiling point refrigerant by absorption of heat from said chamber and a power unit operated by the expanding low boiling point refrigerant as it absorbs heat from the refrigerating chamber,

a compressor operated by said power unit to draw Vapor from the evaporator, compress said vapor and return the compressed Vapor to the evaporator, together with means to cool the compressed vapor before it is returned to the evaporator.

4. The method of utilizing, in a refrigerating system, the energy of expansion of a low boiling point refrigerant which comprises vaporizing said low boiling point refrigerant by absorption, of heat from a space to be refrigerated, using the energy of the vapor produced to do mechanical work lifting a liquid, and varying the work-load by varying the height through which the liquid is lifted to control the extent of refrigeration.

5. In heat exchange apparatus of the refrigeration type the combination with a refrigeration chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a condenser for a low boiling point refrigerant in heat exchange relation with said low temperature refrigerant receptacle, an evaporator to evaporate said low boiling point refrigerant by absorption of heat from said chamber, a circuit through which said low boiling point refrigerant can fiow from the condenser to the evaporator and back to the condenser, means associated with said circuit to cause fluctuations of pressure in one part of the circuit and means associated with the circuit responsive to said fluctuations of pressure including a working liquid serving the function of a piston to cause flow of low pressure refrigerant from the condenser to the evaporator.

6. Apparatus, as defined in claim 5, wherein the means for causing fluctuations of pressure is automatically responsive to the pressure of the vapor of the low boiling point refrigerant.

7. In heat exchange apparatus of the refrigeration type the combination with a refrigera tion chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a condenser in heat exchange relation with said low temperature refrigerant receptacle, an evaporator to evaporate said low boiling point refrigerant by absorption of heat from said chamber, a circuit through which said low boiling point refrigerant can-flow from the condenser to the evaporator and back to the condenser, a prime mover comprising apower chamber associated with said circuit, a compresser chamber, a conduit connecting said chambers, a liquid movable to and fro between said chambers, means operating automatically upon flow of liquid to and from the power chamber to connect said chamber alternately with the evaporator and the condenser to cause flow of liquid to and from said power chamber.

8. In heat exchange apparatus of the refrigeration-type, the combination with a refrigeration chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a low boiling point refrigerant in heat exchange relation with said low temperature refrigerant receptacle, evaporator means to evaporate said low boiling point refrigerant by absorption of heat from said chamber, apower unit operated by the expanding low boiling point refrigerant as it absorbs heat from the refrigerating chamber,'said'power unit comprising a mercury pump having upper and lower chambers and a conduit connecting the same, a cooling coil for the unit into which circulating refrigerant vapor is forced by the flow of mercury to said lower chamber, means for connecting the upper chamber alternately to the evaporator and to the condenser,

means for connecting the lower chamber alternately to the evaporator and to the cooling coil,

to cause the mercury to flow from the lower chamber to the upper chamber and to return to the upper chamber, and means for returning condensed low temperature refrigerant from the condenser to the evaporator.

9. In heat exchange apparatus of the refrigeration type, the combination with a refrigeration chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a low boiling point refrigerant in heat exchange relation with said low temperature refrigerant receptacle, evaporator means to evaporate said low boiling point refrigerant by absorption of heat from said chamber, a power unit operated by the expanding low boiling point refrigerant as it absorbs heat from the refrigerating chamber, said power unit comprising a mercury pump having upper and lower chambers and a conduit connecting the same, a conduit connecting said upper chamber to the evaporator, a float valve closing said conduit but arranged to be lifted by mercury flowing into said upper chamber to admit vapor, means for holding said valve in open position to permit flow of mercury from the upper chamber to the lower chamber and a connection between said upper chamber and the condenser to permit flow of vapor to the condenser.

10. 'In heat exchange apparatus of the refrigeration type the combination with a refrigeration chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a condenser for a low boiling point refrigerant in heat exchange relation with said low temperature refrigerant receptacle, an evaporator to evaporate said low boiling point refrigerant by absorption of heat from said chamber, a circuit through which said low boiling point refrigerant can flow from the condenser to the evaporator andback to the condenser, a pump associated with said circuit for causing a circulation of low boiling point refrigerant having a power chamber, a work chamber, a working liquid in said chambers movable from one chamber to the other and valve means for intermittently connecting the power chamber to the said evaporator to receive pressure therefrom.

11. In heat exchange apparatus of the refrigeration type the combination with a refrigeration chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a condenser for a low boiling point refrigerant in heat exchange relation with said low temperature re frigerant receptacle, an evaporator to evaporate said low boiling point refrigerant by absorption of heat from said chamber, a circuit through which said low boiling point refrigerant can flow from the condenser to the evaporator and back to the condenser, a pump associated with said circuit for causing a circulation of low boilin point refrigerant having a power chamber, a work chamber, a working liquid in said chambers movable from one chamber to the other, a valve operated in response to flow of working liquid into the power chamber to close the exhaust port and open the inlet port of the power chamber.

12. In heat exchange apparatus of the refrigeration type the combination with a refrigeration chamber to be cooled of a receptacle adapted to contain a low temperature refrigerant, a condenser for a low boiling point refrigerant in heat exchange relation with said low temperature refrigerant receptacle, an evaporator to evaporate said low boiling point refrigerant by absorption of heat from said chamber, a circuit through which said low boiling point refrigerant can flow from the condenser to the evaporator and back to the condenser, means associated with said cir cuit and deriving its operating power from the circuit itself to cause fluctuations of pressure in one part of the circuit and means associated with the circuit responsive to said fluctuations of pressure to convert a part of the energy of the fluctuating pressure into mechanical work comprising a working liquid other than the refrigerants actuated by the fluctuating pressure.

DAVID H. KIILEFFER. 

